The present exemplary embodiments relate to media (e.g., documents, paper or the like) handling systems and systems for printing thereon and is especially applicable for printing systems comprising a plurality of associated image output terminals (“IOTs”).
The subject application is related to the following U.S. patents:    U.S. Pat. No. 7,123,873, issued Oct. 17, 2006, for “Printing System with Inverter Disposed For Media Velocity Buffering and Registration”;    U.S. Pat. No. 7,136,616, issued Nov. 14, 2006, for “Parallel Printing Architecture Consisting of Containerized Image Marking Engine Modules”;    U.S. Pat. No. 7,742,185, issued Jun. 22, 2010, for “Print Sequence Scheduling for Reliability”; and    U.S. Pat. No. 7,024,152, issued Apr. 4, 2006, for “Printing System with Horizontal Highway and Single Pass Duplex”.
Printing systems including a plurality of IOTs are known and are generally referred to as tandem engine printers. See U.S. Pat. No. 5,568,246. Such systems facilitate expeditious duplex printing (both sides of a document are printed) with the first side of a document being printed by one of the IOTs and the other side of the document being printed by another so that parallel printing of sequential documents can occur. The document receives a single pass through the first IOT or marking engine, is inverted and then a single pass through the second IOT for printing on the second side, so effectively the document receives a single pass through the system but is duplex printed. Single pass duplex printing using two printers can be twice as fast as duplex printing in a single IOT. Such tandem printing systems may simply consist of a feed source capable of delivering sheets to the first IOT, the first IOT, a transport communicating sheets from the first to the second IOT, the second IOT, and a finishing module. It should be appreciated that the described printing system offers no advantage over a single IOT for simplex printing productivity.
One approach for constructing tandem printing systems having increased simplex productivity is to provide each IOT with a separate and dedicated feed source for the paper or print media being processed. Consequently, for a two IOT system, this means that operators must access two different places to load media, and then those feed trays will only deliver media directly to their respective marking engine. From an operability standpoint, having all the media located in a single place would be an advantageous feature, at least for the operator. In addition, with separate and dedicated feed sources it is difficult to provide a media path allowing all the media to be delivered to any marking engine, or to selected output devices. Although some known parallel printing systems provide variable route media paths, there is a need for a printing system which can provide essentially a single media feed source to a plurality of marking engines while also providing a variable route media path so media sheets can be directed from the single source to any marking engine or a by-pass path, within the overall system.
Especially for multi-engine, parallel printing systems, architectural innovations which effectively provide maximum media path variability can enhance document process path reliability and increase system efficiency.